Recently, laminated ceramic devices that are formed by laminating ceramics and arranging conductor patterns inside and outside the laminated ceramics without molding the ceramics themselves into a complex shape and that can be made small without eliminating various electronic properties of the ceramics have been utilized in various fields.
Typical laminated ceramic devices include a laminated ceramic condenser in which dielectric ceramics are used. Nowadays, laminated ceramic condensers with various capacities and sizes are delivered from electronic component manufacturers that are engaged actively in developing condensers with high capacity and a small size.
Recently, this laminating technique also has been used for manufacturing a resonant device such as a band-pass filter for a microwave band used in a portable telephone. Conventionally, such a resonant device was formed by molding dielectric ceramics into a cylindrical shape and metallizing its outside, thus obtaining a coaxial resonator. Further, a plurality of the coaxial resonators are arranged to form a band-pass filter. On the contrary, a laminated band-pass filter is constructed by forming conductor patterns, which are electrically equivalent to a coaxial filter, inside dielectric ceramics by the laminating technique. The laminated band-pass filter can be made very small compared to a conventional coaxial type. Therefore, the laminated band-pass filter has been an essential device for making a portable telephone terminal small these days. In addition, dielectric ceramics have been applied to laminated devices, which have been adopted in an isolator and a circulator, or in a field of a laminated ceramic multilayer substrate using ceramics having relatively low specific inductive capacity and the like.
Similarly, in a field of piezoelectric ceramics, the piezoelectric property has been obtained by forming electrodes outside a device conventionally. However, recently, by the laminating technique, a method for making the device small by forming a conductor inside piezoelectric ceramics, a method for obtaining higher output without changing a device size, a method for reducing power consumption, and the like have been proposed. A method for applying such methods to a member for an acceleration sensor, a flat-type resonant chopper, or the like has been proposed.
However, in a conventional laminated ceramic device, the thickness of each conductor section on upper and lower surfaces is almost the same as the difference in level between the conductor section and the section where no conductor section is formed as disclosed in Unexamined Japanese Patent Application Tokkai Hei 5-343943. In such a structure, when polishing the device after forming the conductor section for the purpose of characteristics adjustment or the like, the conductor section is polished as well. Consequently, there has been a problem that the conductor section becomes very thin or the conductor section is completely removed and the like. Moreover, even if these problems are avoided, in the case of using a conventional structure of a conductor section formed on each of the upper and lower surfaces, such problems that the conductor section comes off from the part having a big difference in level when handling it later and the like occur, which have caused defects.
In a method of manufacturing a conventional device, since conductor sections on the upper and lower surfaces are formed after sintering the ceramics, there have been such problems that it is difficult to arrange the position relationship between conductors inside ceramics and conductors on the upper and the lower surfaces accurately and that a manufacturing cost is high.